The title for best grid-tie solar inverter has never been closer as many of the top manufacturers release advanced new models with clever online monitoring and smart home energy management features. The hype around home battery systems or hybrid systems is also growing, but it is early days for batteries and the majority of solar installations still require a dedicated solar inverter. Even the renowned Tesla Powerwall 2 with its inbuilt inverter requires an additional solar inverter to work with a solar array.
Solar Inverter function & problems
The solar inverter is the most sophisticated part of any grid-tie solar system and unfortunately it's also the part most likely to have issues. This is not surprising considering inverters are usually located outside in harsh weather conditions including rain, humidity and extreme heat, all while generating thousands of watts of power for up to 10 hours a day. This is why it's important to use a quality inverter and mount it in a sheltered location if possible.
Due to extreme variations in humidity and temperature it is likely that many inverters mounted outdoors will experience a fault at some point during their lifetime. However the life of a solar inverter can be significantly increased by locating it inside a garage, under a carport and out of direct sunlight.
Solar panels can also develop problems over time which can result in poor performance, but unlike a faulty inverter this will generally not result in complete system shutdown. With this in mind it is worth while paying the additional cost for a reputable manufacturer (one which has been in good business standing for 5+ years and with extended warranties if available.
Warranty and Service
Fronius, SMA and SolarEdge have ranked on top of the list for many years due to the low failure rates and great service as they usually ship replacement units in 3-5 business days. Fronius and SMA are available with 10 year warranties while SolarEdge offer a leading 12 year manufacturers warranty. Many of the lesser known 'value' brands will only repair a faulty unit if it is shipped to them (at the owner costs) and returned which often takes weeks and sometimes months. This will have a much greater financial impact due to system downtime.
Solar Inverter Types
String Solar Inverters
This review is focused on 'string' solar inverters which use a string of solar panels linked together in series. String inverters are the most common type of inverter used in Europe, Australia, & Asia, and growing in popularity in the US where micro inverters are very popular.
The new generation hybrid solar inverters combine a solar and battery inverter together in one simple unit. These inverters are becoming more competitive against solar inverters as hybrid inverter technology advances and batteries become cheaper and more appealing. See our detailed hybrid/off-grid inverter review.
Off-grid or stand-alone power systems require powerful battery inverters with inbuilt chargers that can be setup as either AC or DC coupled systems. The modern flexible off-grid inverter/chargers, also known an multi-mode inverters, can be used to create advanced hybrid grid-connected systems. See our best off-grid solar system review for more information.
Micro inverters, also known as micros are very small solar inverters attached directly to individual solar panels. Since each micro inverter and panel operate independently, they are a great option for complex roof layouts and locations with shading issues. Despite the slightly higher cost, micros are very popular in North America due to Enphase’s strong presence and the many advantages they offer over string inverters.
Inverter Rating Criteria
The following criteria was used to determine the best solar string inverters available on the market together with continuous feedback from solar installers and industry specialists. Note this comparison is focused on the common grid-tie solar 'string' inverters (single phase) although the larger commercial 3-phase inverters from the same manufacturers are equally well regarded.
Quality & Reliability
Service & Support
There is a considerable price difference between the hundreds of different solar inverters available. For example a low-end 5kW inverter can start from as low as $850, while a premium quality 5kW inverter with 10+ year warranty may cost $1800 or higher. However considering the higher failure rates of many low-end/cheap inverters and difficulty claiming warranties we recommended you invest in a higher quality unit. As a common saying in the solar industry goes 'the cheapest product will cost you more in the long run'.
Best Solar Inverters 2019
1. Fronius - Primo and Galvo
2. SolarEdge - SE and HD wave
3. SMA - Sunny boy
4. Sungrow - SG-KLT
5. ABB - UNO
Best Commercial Inverters (3 phase)
1. Fronius - Symo and Eco
2. SMA - Sunny Tripower & Core 1
3. SolarEdge - SE 3-phase
4. Sungrow - SG-KTL range
5. ABB (FIMER) - Trio, PRO and PVS
Have your say - Solar professionals feedback
In addition to continuous feedback from our solar specialists the clean energy reviews team invite all solar industry professionals and installers to provide feedback (positive or negative) from experience with any inverters (string, micro, off-grid & hybrid). Click link below.
top 5 Solar inverters - Residential
Below we describe the top 5 residential solar ‘string’ inverters for 2019 based on quality, features, monitoring, warranty and service, together with feedback solar installers and industry professionals around Australia. There are also a number of popular inverter brands which are highly regarded by many solar installers listed in the runner up section below.
Fronius Inverters have surged in popularity since the release of the snap-in design 5 years ago. The high-end Austrian manufactured inverter range has definitely become the inverter of choice for many domestic and commercial solar installations. Although customers are also raving about the performance and reliability, plus the great customer service from Fronius in Australia. The high demand for the popular single phase Fronuis Primo solar inverters used for residential installations has resulted in some supply issues at times and there have been some minor faults, but overall feedback is extremely positive and any issues have been promptly corrected. An additional free 5 year extented warranty is available when the inverter is registered online and provides a total 10 warranty period.
See the detailed Fronius Solar Inverter Review article.
Active cooling system
One of the main reasons for Fronius’s reliability and performance is due to the ‘active cooling’ system incorporated into all Fronius snap-in inverters. The fan forced cooling system extracts heats at a higher rate which reduces thermal stress and increases total generation in high ambient temperatures. All power electronics have a maximum operating temperature after which the power needs to be reduced to prevent overheating and potential damage, this is where active cooling can improve both reliability and performance.
One of the clever features is the integrated solar DC isolator which means an external isolator box is not required, resulting in a much neater installation. Also the unique snap-in design makes servicing and installation very simple.
The Fronius 3-phase Symo and ECO inverters are also widely regarded as the best commercial inverters and have dominated the larger scale solar market due to the high quality and proven reliability.
Wifi monitoring comes standard with all inverters via the Fronius Solar.Web. The addition of the Fronius Smart meter enables monitoring of energy generation and consumption and can be used as a complete home energy monitoring system. A free solarweb smart phone app is also available for android of iOS. There is also the option of adding the Fronius Ohmpilot which is designed to automatically use excess solar energy to heat water.
See the detailed Fronius Primo Inverter specification sheet
SolarEdge inverters have becoming increasingly popular in Australia, USA and around the world over the last few years due to the unique design using DC optimisers which enable individual panel level monitoring and control. See the detailed SolarEdge Review article.
The SolarEdge HD wave (SE-H series) inverters are available in a wide range of sizes from 2.5kW to 10kW and are one of the smallest and lightest inverters available. They are also some of the most efficient inverters at 99% for the larger 5 - 10KW models. This is achieved through the use of advanced thin-film capacitors and digital processors to produce an AC output with very low losses. All Solaredge inverters must be installed with additional DC optimisers on each panel as described below. DC optimisers perform part of the job of a typical string inverter and are the reason Solaredge was able to develop such a small, efficient inverter.
The biggest advantage SolarEdge has over the competition is panel level monitoring and power optimisation through the use of panel mounted DC optimisers.
DC Optimisers are small electronic modules attached to the back of the solar panels which allow for individual panel level monitoring and power optimisation. Previously individual panel monitoring was only obtained through the use of micro-inverters, plus some add-on optimisers such those from Tigo Energy. Solaredge Optimisers enable longer strings of panels (up to 22 modules), increased safety in addition to reducing the detrimental effects of shading and panel faults, plus provide early detection of potential issues. However they do also add to the complexity of the system and being an electronic device mounted on the roof may have the potential to cause issues in the longer term.
Panel shading a problem? For complex roof profiles or installations with shading issues this would be the inverter of choice, however for smaller systems or strings with 6 panels or less micro inverters are better suited.
SolarEdge also has an industry leading 12 year warranty period.
SolarEdge inverters have 'optional' wifi which together with the optimisers can provide power output data for each panel individually. This is great for both system monitoring and a very good tool for fault detection, especially for installers. Also SolarEdge definitely have one of the best smart phone apps for remote system monitoring.
See detailed SolarEdge Solar Inverter specification data sheet
German manufacturer SMA Solar Technologies was regarded as the best string inverter manufacture on the market before the Fronius snap-in series took the top spot in 2016. SMA's decision to locate the manufacturing of the new AV series inverters in China rather than Germany also hurt the companies sales and reputation. However, SMA relocated all manufacturing back to Germany in 2019. The larger capacity 3-phase commercial inverters from SMA are all manufactured in Germany and still widely regarded as some the best commercial inverters on the market, with the Sunny Tripower and Core 1 inverters being a trusted, reliable option for many years.
SMA inverters have a proven track record for reliability and are generally considered one of the highest quality inverters available. Local service and support is very reliable and SMA provides an optional extended 10 to 20 year warranty.
Unlike the older model Sunny boy TL inverters the latest AV inverter series from SMA does not have a display panel and relies solely on wifi communication for setup and monitoring. Display-less inverters are becoming an industry trend as many other manufacturers are releasing new models without a display. A digital display in an outdoor environment can be problematic so this may reduce faults and warranty issues in the long term, but only if the communications is very reliable and stable. Without a wifi signal and no display can make things difficult to troubleshoot if a problem does occur.
See the detailed SMA solar Inverter review article.
SMA have a great free online monitoring package available known as the Sunny portal. Since the new AV series Sunny boy inverters have no display for setup and monitoring reliable communications is vital to the success of the new models. Most SMA inverters now have the wifi webconnect capability as standard and together with the additional Sunny home manager 2.0 (energy meter) although rather expensive it creates a complete home energy monitoring system. The only downfall is the SMA mobile app which looks outdated and has had poor feedback, particularly the Android App version.
See full SMA solar inverter specification data sheet
Founded back in 1997 by a university professor Sungrow is one of the largest suppliers of solar inverters globally and a leading Chinese inverter manufacturer. The residential SG-KTL Sungrow inverters have become very popular among Australian installers due to the competitive price and great reliability record, plus Sungrow is a very large player internationally and has a good reputation for service and quality compared to most Chinese inverter manufacturers. Sungrow offer very good support from the Sydney based office in Australia which has further helped improve their reputation.
In addition to the well regarded range of solar inverters Sungrow also manufacture one of the best value hybrid solar inverters on the market - the new generation SHK5-20 inverter is a very affordable hybrid inverter for home energy storage systems and comes with an optional back-up device for protection during a blackout.
Sungrow inverters include Wifi monitoring as standard on all residential models and use the online new modern monitoring portal ISolarCloud which is a huge improvment. The free smart phone App is also very simple and works well.
Update July 2019 - In a surprising move ABB decided to sell it’s entire solar inverter division to FIMER, a well established Italian based inverter manufacturer who will take over ABB’s solar division in early 2020.
ABB is a premium manufacturer offering a range of high quality string solar inverters but previously gained a bad reputation from the old 'Aurora' branded inverters. ABB acquired Aurora 'Power-one' back in 2013 and thus have to deal with many warranty claims and service issues from the unreliable old generation Aurora inverters.
Our specialists have highlighted somewhat slow customer service compared to other manufacturers even though ABB is a well respected industrial giant. ABB's reputation has improved on the back of the new range of UNO-TL and UNO-TL-DM-PLUS single phase solar inverters.
The new UNO inverters have the common plug & play interfaces, are lighter, more compact and have wifi included on all models.
ABB are not well known for their monitoring but have a updated Plant Viewer monitoring portal and ‘Energy Viewer’ mobile App. The portal offers all the basic information but unfortunatley it is a little limited and doesn’t provide more technical data such as individual string outputs or voltages, which helps with monitoring and troubleshooting. A Wifi logger card (VSN300) can be installed on all older UNO and TRIO (3-phase) inverters.
Solar Inverters - Runners up
Besides the most popular inverters on the market it is worth highlighting some of the other well known or up and coming inverter manufacturers. Many of these brands are generally very reliable but only let down by the lack of service and support when an issue occurs. Huawei is the most recent manufacturer to enter the competitive residential market and so far the Sun2000L inverter series appear to be very reliable and offer loads of advanced features.
Huawei Sun2000L Inverter
Chinese communications giant Huawei stormed into residential solar market in 2018 with a compact, lightweight solar inverter packed with features. Due to the huge volume of commercial inverters sold globally Huawei are currently the largest producer of solar inverters globally and have invested billions into research and development over the last decade.
The first residential solar inverter from Huawei is the SUN2000L which is available in a range of sizes from 2 to 5kW. It also functions as a hybrid inverter and is extremely compact and lightweight coming it at 10.6kg. The inverter is in some ways similar to the SolarEdge HD wave inverter which uses optimisers for individual panel optimisation much like micro inverters. However unlike the HD wave the SUN2000L can function with or without optimisers. As a hybrid system the Huawei inverter uses a built in 'high voltage' DC coupling battery interface which is compatible with the popular LG chem RESUH batteries. However there is no back-up power supply function available yet but we are told it is in development.
The new FusionSolar online monitoring portal is much better than the previous NetEco and offers an easy to read interface and many more advanced monitoring and data logging features. The new common FusionHome app is also used for inverter setup and direct connection via a local wifi network.
For more information see our complete Huawei inverter review article. Residential sales seem to be relatively small at this stage but with the many advanced features it will be very interesting to see how this inverter performs against the premium manufacturers, especially once the battery backup unit becomes available.
See full specifications of the Huawei SUN2000L inverter series here.
Solax Power is a relatively new inverter manufacturer which was largely unkown in the industry until they launched the economical battery X-hybrid inverter. Solax is a subsiduary of the the much larger Suntellite Group in China which manufactures solar cells, panels and inverters with a strong emphasis on research and development. Solax Power also has a strong global presence and an Australian support office located in Melbourne. The current X1 range of solar inverters may not have the sleek designs of the European rivals but at close to half the price you wouldn't expect them to compete on this level, their slogan sums them up nicely 'simple, reliable, efficient'.
One of the more advanced inverter options from SolaX is the affordable X-hybrid unit which is one of the most economical ‘battery ready’ solar inverters available. Solax is also one of the few inverter manufacturers to produce large 3-phase hybrid battery inverters for larger residential and commercial applications.
The Solax online monitoring portal V2 is quite impressive and offers access via smart phone apps or web interface with battery management features for hybrid systems and email reporting, although the wifi dongle is an optional extra.
See the full Solax Inverter specification here
Delta is generally well regarded by installers as one of better value Chinese made inverters. This is not surprising as Delta Group is a global electronics giant which has been manufacturing power control systems around the world since 1971. The older RPI range released a few years back did not become a huge hit with installers but the new more advanced Delta Home Series inverter might be more appealing to installers and customers alike, although there is a lot of competition from the many lower price point inverters on the market. With a 5 year product warranty as standard and an Australian office located in Melbourne, it is one of the more trusted value level inverters available. Monitoring is via the new cloud based mydeltasolar app.
GoodWe is a large, well known Chinese inverter manufacturer established in 2010. The new generation Goodwe DNS series has had great feedback from installers so far. Many Chinese brands have a mixed reputation in Australia due to some previous quality issues, but have improved considerably over the last few years.
In addition the vast new Goodwe hybrid inverter range is replacing the older (GW5048D-ES) hybrid inverter which was a standout product from the Goodwe range and quite well regarded in the industry with many other manufacturers incorporating this inverter into various battery energy storage systems (ESS). All Goodwe inverters include Wifi monitoring as standard. The Warranty on the DNS series is 5 years full options to extend the warranty up to 25 years.
See the full Goodwe DNS solar inverter specifications data sheet
Ingeteam is a well known, premium European inverter manufacturer which is new to the competitive small scale Australian solar market, despite being a large multinational company and having a long history in manufacturing power conversion equipment. The company of Spanish origin has advanced R&D capabilities and currently manufacturer a wide range of quality solar and hybrid inverters for the residential and commercial markets, in addition to much larger utility scale central solar inverters.
The residential (2.5 - 6kW) 1Play TL-M series dual MPPT solar inverters appear to be well engineered with many advanced features and monitoring, however as yet none of our Australian specialists have had any direct experience. Looking forward to seeing more and reviewing the Ingeteam inverters during 2019.
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